Improvements in or relating to building structures

ABSTRACT

A wall of a building structure, the wall comprising: inner and outer face surfaces formed from glass fibre reinforced board; a support structure comprising one or more rigid components positioned between the inner and outer face surfaces; and a quantity of low-density cellular lightweight concrete (CLC) which substantially fills the space between the inner and outer face surfaces.

This invention relates to building structures, and in particular tobuilding structures having walls which must provide a certain level ofthermal insulation.

In many countries regulations are in place governing the level ofthermal insulation that must be provided by external and/or internalwalls of structures in which people will live and/or work, such ashouses, offices and other commercial premises, and hotels.

Conventional insulating internal walls in modern structures are formedby providing generally parallel opposing sheets of material, such asgypsum or chipboard, having a gap or cavity therebetween. This gap isthen filled with insulation material such as a rigid foam or a mineralwool.

This conventional construction suffers from drawbacks, however. It canbe difficult to control the level of thermal insulation that isachieved. Also, over time the properties of the insulation material arelikely to change, thus reducing the level of thermal insulation that isprovided.

It is an object of the invention to provide an improved construction ofthis type.

Accordingly, one aspect of the present invention provides a wall of abuilding structure, the wall comprising: inner and outer face surfacesformed from glass fibre reinforced board; a support structure comprisingone or more rigid components positioned between the inner and outer facesurfaces; and a quantity of low-density cellular lightweight concrete(CLC) which substantially fills the space between the inner and outerface surfaces.

Advantageously, the inner and outer face surfaces are substantiallyparallel with each other.

Preferably, the density of the CLC is less than 200 kg/m³.

Conveniently, the face surfaces are formed from glass fibre reinforcedconcrete (GRC).

Advantageously, the low density CLC substantially fills the spacebetween the inner and outer face surfaces over the entire height of thewall.

Preferably, the inner and outer face surfaces are attached to, andsupported by, the support structure.

Conveniently, the face surfaces are spaced apart from the supportstructure, to provide a gap between the support structure and each ofthe face surfaces.

Advantageously, the inner and outer face surfaces are each formed from aplurality of sheets of glass fibre reinforced board.

Preferably, the support structure comprises a series of spaced-apartsupports, and each sheet is attached to at least one of the supports.

Conveniently, each support has an inner side and an outer side, sheetsof the inner face surface are attached to the inner side and sheets ofthe outer face surface are attached to the outer side.

Advantageously, each sheet has widened regions at opposing edgesthereof, with a narrower region between the widened regions.

Preferably, each sheet has widened regions at each of its edges.

Conveniently, the support structure is entirely or substantially formedfrom light gauge steel (LGS).

Another aspect of the present invention provides a building structureincorporating a wall according to any one of the above.

A further aspect of the present invention provides a building structurecomprising two or more walls, each according to any one of the above,wherein the low density CLC within the two or more walls comprises aunitary, continuous and unbroken quantity of CLC.

Advantageously, the building structure further comprises a ceiling or afloor, which forms part of the same storey of the structure as thewall(s), wherein the floor or ceiling comprises at least one facesurface formed from glass fibre reinforced board, and the floor orceiling contains a quantity of low-density CLC which forms a unitary,continuous and unbroken quantity of CLC along with the CLC which iswithin the wall(s).

Preferably, the building structure comprises two or more stories, eachincluding one or more walls according to any one of the above.

Another aspect of the present invention provides a method of forming awall of a building structure, the method comprising: providing inner andouter face surfaces formed from glass fibre reinforced board; providinga support structure, comprising one or more rigid components positionedbetween the inner and outer face surfaces; and pouring a quantity oflow-density CLC into the space between the inner and outer facesurfaces, so that the low-density CLC substantially fills the spacebetween the inner and outer face surfaces.

Conveniently, the method comprises: providing the support structure;attaching the outer face surface to the support structure; and attachingthe inner face surface to the support structure.

Advantageously, the method further comprises the step, after the step ofattaching the outer face surface to the support structure, but beforethe step of attaching the inner face surface to the support structure,of installing components of one or more service, such that, once thestep of attaching the inner face surface to the support structure hasbeen completed, the components of the one or more service are locatedbetween the inner and outer face surfaces.

Preferably, the components of the one or more service include one ormore of power cables, water pipes, data cables, and ventilationcomponents.

Conveniently, the method comprises providing an inner and outer facesurfaces for one or more further walls; and pouring the quantity oflow-density CLC so that the spaces between the inner and outer facesurfaces of all the walls are simultaneously filled.

Advantageously, the method further comprises the step of providing oneor more further face surfaces to define a ceiling space, above thewalls, or a floor space, below the walls; and pouring the quantity oflow-density CLC so that the walls and the ceiling space of floor spaceare filled, or partially filled, with the low-density CLC in oneoperation.

Preferably, the method comprises the steps of: placing face surfaces ofglass fibre reinforced board to define internal spaces for one or morewalls, and for a ceiling space above the walls, or a floor space belowthe walls, wherein the internal spaces for the one or more walls and theceiling space or floor space are in fluid communication with each other;and pouring a quantity of a low-density CLC to fill, at least partially,the internal spaces for the one or more walls and the ceiling space orfloor space in one operation.

Conveniently, the method comprises the step of filling or substantiallyfilling the internal spaces for the one or more walls, to the fullheight of the walls, in the one operation.

Advantageously, the method comprises the steps, for a single storey ofthe building structure, of: dividing the storey into two or moresections, each section including one or more walls and part of theceiling space or floor space; pouring a first quantity of the CLC intothe first section to fill, at least partially, the internal spaces forthe one or more walls and the part of the ceiling space or floor spacein a first operation; and pouring a second quantity of the CLC into thesecond section to fill, at least partially, the internal spaces for theone or more walls and the part of the ceiling space or floor space in asecond operation.

A further aspect of the present invention provides a method ofconstructing a wall of a building structure, the method comprising:receiving a minimum insulation value for the wall; providing inner andouter face surfaces formed from glass fibre reinforced board; from theinsulation properties of the inner and outer face surfaces, and of alow-density CLC, calculating the thickness of CLC that must be presentbetween the inner and outer face surfaces in order for a wall,comprising the inner and outer face surfaces with the space therebetweensubstantially filled by the low-density CLC, to have an overallinsulation which is equal to or greater than the minimum insulationvalue; placing the inner and outer face surfaces at a distance from oneanother which is at least as great as the calculated thickness; andfilling the space between the inner and outer face surfaces with thelow-density CLC.

Preferably, two or more walls of the same storey of the buildingstructure have different minimum insulation requirements, the methodcomprising the steps of calculating the thickness of the low-density CLCthat must be present between the inner and outer face surfaces of eachwall in order for each wall to meet its minimum insulation requirement;placing the inner and outer face surfaces of each wall at a distancewhich will allow the finished wall to have an insulation value which isequal to, or greater than, the minimum insulation value for eachrespective wall; and filling the inner and outer face surfaces of eachwall with the same quantity of low-density of CLC in a single operation.

Another aspect of the present invention provides a method ofconstructing a wall of a building structure, the method comprising thesteps of: receiving a minimum insulation value for the wall; receiving amaximum thickness for the wall; calculating a minimum density for alow-density CLC wherein, for a finished wall of a thickness which isequal to or less than the maximum thickness comprising the inner andouter face surfaces with the space therebetween substantially filledwith the low-density CLC, will have an insulation value that is equal toor greater than the minimum insulation value; preparing a low-densityCLC having at least the calculated density; and pouring the low-densityCLC into the space between the inner and outer face surfaces, so thatthe low-density CLC substantially fills the space between the inner andouter face surfaces.

In order that the present invention may be more readily understood,embodiments thereof will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 shows a series of supports suitable for use with the presentinvention;

FIG. 2 shows the supports of FIG. 1 along with an outer face surface;

FIG. 3 shows the supports of FIG. 2 with both inner and outer facesurfaces;

FIG. 4 shows a side view of panels, used to form a face surface,attached to one of the supports;

FIGS. 5 and 6 show a wall embodying the present invention before andafter the wall is filled with CLC, respectively;

FIG. 7 shows one examples of a panel suitable for use in forming anouter face surface;

FIG. 8 shows a stage of formation of two walls and a ceiling, inaccordance with the invention; and

FIG. 9 shows a more close-up view of the junction of the walls and theceiling.

The construction of a single wall will be described in the firstinstance, by way of illustration of some of the principles of thepresent invention.

With reference firstly to FIG. 1, a first stage in the construction of awall embodying the present invention is shown.

A number of spaced-apart vertical supports 5 are first installed inposition, to provide a support structure for the wall. Three supports 5are shown in FIG. 1, although any number of supports may be used. Thesupports 5 shown in FIG. 1 are aligned with each other, and this willgenerally be preferred for the construction of a straight wall. However,the skilled reader will understand that the supports may be arranged inany suitable manner, depending on the shape and size of the wall to beconstructed.

In the example shown in FIG. 1, each of the supports 5 takes the form ofa column having an omega profile. Each support 5 has a rear wall 32 andtwo side walls 33, and one open face 34, which is substantially oppositethe rear wall 32. A pair of lips 35 extend inwardly from free edges ofthe two side walls 33, partially occluding the open face 34.

The invention is not limited to this, however, and any suitable kind ofsupport elements or structure can be used with the invention, includingbeams, rods or girders. The elements of the support structure may bearranged in a lattice, may comprise a series of generally parallelmembers, or otherwise be arranged in any other suitable way to providethe required support for the intended finished structure.

The supports 5 are preferably fixed in place with respect to the ground.Each support 5 may be, for example, 0.2 to 0.3 m wide, although theinvention is not limited to this.

In preferred embodiments of the invention, the supports 5 are formedfrom light gauge steel. In preferred embodiments, all or substantiallyall of the components of the support structure are formed from lightgauge steel. The thickness of the components of the support structure ispreferably no more than 3 mm.

As a next step, a first or outer face surface 1 is installed, attachedto and supported by one of the side walls 33 of each of the supports 5,as shown in FIG. 2. The first face surface 1 preferably comprises acontinuous or substantially continuous planar surface, which extendsover all or substantially all of the height of the intended finishedwall. In FIG. 2 the first face surface 1 and the supports 5 are ofsubstantially the same height, although in practice the supports 5 maybe higher than the first face surface 1, as will be explained in moredetail below.

The first face surface 1 preferably extends down to ground level.

The spaces between the supports 5 will, once the wall is complete, bewithin the wall itself. As a next step, other components that arerequired to be ultimately embedded or contained within the wall arepositioned between, and/or attached to, the supports 5. For example,water/plumbing pipes, electrical cables and/or ventilation components(“services”) may be installed at this stage.

Some of these components may need to pass through one or more supports5. Access slots or apertures (not shown) may be provided through thesupports 5 as needed to allow the service components to be installed inrequired places and extend through the wall to desired locations.

As a next step, shown in FIG. 3, an inner or second face surface 2 isinstalled on the opposite side of the supports 5 from the first facesurface 1. The face surfaces 1, 2 are preferably generally parallel witheach other.

The face surfaces 1, 2 are preferably formed from glass fibre reinforcedboard. As the skilled reader will be aware, glass fibre reinforced boardtakes the form of sheets of material comprising glass fibre heldtogether by suitable substrate. In preferred embodiments of theinvention, the face surfaces 1, 2 are formed from glass fibre reinforcedconcrete (known as GFRC or GRC). As the skilled reader will be aware,GRC consists of glass fibres (preferably high-strength and/oralkaline-resistant glass fibres), embedded in a concrete matrix. GRC canbe produced by a spray procedure or a premix procedure. While either ispossible with the present invention, using a premix approach ispreferred. It is also preferred that the proportion of glass fibres inthe GRC is at least 1%.

In preferred embodiments of the invention, the face surfaces 1, 2 areeach formed from a plurality of sheets of GRC. For instance, sheets ofapproximately 1 m by 1 m may be produced, and arranged edge-to-edge tomake up each of the face surfaces 1, 2. Sheets of this size may readilybe produced on-site, thus increasing the efficiency and adaptability ofthe building procedure.

Each of the sheets may be attached directly to a side surface 33 of oneof the supports 5. For example, a first support 5 may have a series ofsheets attached thereto extending from the ground up to the top edge ofthe face surface 1, 2, with the top edge of each sheet lying against thebottom edge of the next-highest sheet. An adjacent second support 5 mayalso have a series of sheets attached thereto, with a side edge of eachsheet attached to the second support lying against a side edge of asheet which is attached to the first support. In this way, a pluralityof sheets can be attached to the supports 5 and fit together to form acontinuous face surface 1, 2.

FIG. 4 shows a side view of a sheet 42 of GRC attached to one of thesupports 5. As can be seen in this figure, the sheet has widened regions43, 44 at its upper and lower ends, with a narrower region 45therebetween. The narrower region 45 is, in this example, formed by arecess on the inner side of the sheet 42, i.e. the side facing thesupport 5, so the outer-facing side 46 of the sheet 42 is planar, orsubstantially planar.

On its upper and lower edges 47, 48, the sheet 42 has connectionapertures 49. Each connection aperture 49 comprises a bore, lined with asturdy material such as steel, with an anchor 50 (which may take theform of a pin) protruding from the bore into the interior of the sheet42 by a short distance. Any number of connection apertures 49 may beformed along the upper and lower edges 47, 48 of the sheet 42, but insome embodiments only one connection aperture 49 is formed on each ofthe upper and lower edges 47, 48.

Support arms 51 protrude outwardly from the support 5, and includeupward-facing and downward-facing connection protrusions 52 which areadapted to fit into the connection apertures 49. The connectionprotrusions 52 may, for example, take the form of pins, formed from arobust material such as steel.

As the skilled reader will appreciate, the sheet 42 may be fixed readilyin place with respect to the support 5, by fitting the appropriateconnection protrusions 52 into the connection apertures 49 on the upperand lower edges 47, 48 of the sheet. Further sheets may be installedabove and below the sheet 42, in a similar manner, to form a facesurface 1, 2.

The side view shown in FIG. 4 is taken through a vertical section.However, it should be understood that a view taken through a horizontalsection may be generally identical, including widened sections at theedges of the sheet, connection apertures and support arms withconnection protrusions, as shown in FIG. 4.

The sheet 42 is wider at its edges to provide a sufficient thickness toaccommodate the connection apertures 49 and the associated anchors 50,and to provide sufficient strength at these locations, where thegreatest forces are likely to be experienced. However, the sheet 42 isnarrower in its central section to reduce weight and cost.

Where the edges of the sheets meet each other, a seal is preferablyformed between the sheets, and for instance this may take the form of asilicone seal.

The supports 5 are preferably spaced apart by a distance which is equalor substantially equal to the width of each sheet. This allows adjacentvertical sets of sheets to be attached to adjacent supports 5, as theskilled reader will understand.

The above discussion primarily relates to an unbroken region of astraight wall, formed from sheets of GRC which are of regular andconsistent sizes and shapes. However, sheets will sometimes need to beused which are of irregular or different sizes, for instance where wallsmeet each other, around windows, alcoves or partitions, or where theheight of a wall is not equal to the combined heights of an exact numberof regular sheets. For these purposes, sheets of different shapes andsizes may be created, as the skilled person will readily understand.

Sheets of GRC may also need to be formed which extend in more than oneplane, for instance where an internal wall meets a window aperture.Sheets may need to be produced which have a first portion set at a firstangle (e.g. the part of the sheet corresponding to a region of aninward-facing wall), and a second portion at a second angle (e.g.corresponding to a region of the window aperture), where the first andsecond portions may be at 90° to each other. Sheets of GRC can readilybe produced which have shapes of this nature.

FIG. 5 shows a cross-sectional view through first and second facesurfaces 1, 2, taken at a position between supports 5. In the exampleshown in FIG. 5, a water pipe 7 is shown between the face surfaces 1, 2.An electrical cable 8 also extends up from ground level 4 between theface surfaces 1, 2, and is diverted to one of the face surfaces 1 at anappropriate height for a plug socket (not shown). Apertures may be cutin one or both of the first and second face surfaces 1, 2 to allowservices within the wall to communicate with the outside of the wall.For instance, apertures may be cut for plug sockets, taps, lightfittings, data ports, ventilation, and so on.

In a next step, shown in FIG. 6 a cellular lightweight concrete (CLC) 9,which is initially in a liquid form, is poured into the gap 3 betweenthe face surfaces 1, 2, to fill this gap 3 up to a certain height. Inthe example shown in FIG. 6, the CLC 9 is poured into the gap to fillthe gap up to the level of the tops 6 of the face surfaces 1, 2.

As the skilled reader will understand, CLC is a type of concrete whichincludes a foaming agent, to result in a finished material having airbubbles which displace at least some of the concrete, leading to amaterial which is less dense and more easy to work with than regularconcrete.

In preferred embodiments, a low-density CLC is used. Preferably, thedensity of the CLC is below 250 kg/m³. The density of the CLC ispreferably between 70 and 250 kg/m³, and more preferably between 100 and200 kg/m³. In some preferred embodiments of the invention the density ofthe CLC used is around, or exactly, 150 kg/m³.

A CLC having a density of 150 kg/m³ can be formed by mixing 150 kg ofcement, 62 kg of water, and 890 l of a foam. For these purposes it ispreferred to use a foam which is available, under the name N-600, fromNeopor (a division of BASF) or through worldwide agencies of Neopor.This foam may also be obtained from PBP Berlani Holding Ltd.(contactable at 3rd Floor, 120 Baker Street, London W1U 6TU, UnitedKingdom, on +41 79 66 30 428 or at www.pbpberlani.com).

In a preferred method of formulating the CLC, the mortar consists ofPortland cement Type 1 and water. This must be mixed for a minimum of 30seconds. When the mortar is ready, the foam is added in it. The foammust be stable and the bulk density of the foam should be between 60 gand 80 g per litre. Stable foam can be made with a Neopor Plug & Foamunit. Towards the end of the process, the foam must be mixedhomogeneously into the mortar. The mixing of foam into the mortar takesplace in a mixer, resulting in a very light CLC which is suitable foruse with the present invention.

Suitable machines for the production of the CLC can be obtained from PBPBerlani Holding Ltd.

By way of example, in order to increase the density of the CLC, morecement and water can be included in the mixture. A volumetriccalculation can be used. For instance, if a further 50 kg of cement isincluded in the example mixture given above, this contributes around afurther 16 l of volume to the mixture. If another 1 l of water is added,this gives a total of 17 l extra volume that is added to the mixture. Tocompensate for this, 17 l less of foam should be added. The mixingprocess will remain as explained above.

Conversely, to reduce the density of the mixture, less cement and watercan be included, and the skilled person will realise how this can beachieved.

It is not necessary to use a volumetric approach, and the above aregiven only as examples.

Once the CLC 9 has set, the resulting wall 10 is finished orsubstantially finished.

It is important to note that the face surfaces 1, 2 are not removed oncethe CLC 9 has set, and the face surfaces 1, 2, the CLC 9 and thesupports 5 all form part of the finished wall 10.

It is mentioned above that apertures are formed in the first and/orsecond face surfaces 1, 2 to allow services to communicate with theexterior of the wall. These apertures are preferably formed before thepouring of the CLC.

A wall having a construction of this type may have considerableadvantages with respect to conventional insulating walls. Thecombination of glass fibre reinforced board and CLC will provide a veryhigh level of thermal insulation. The low viscosity of low-density CLCwill ensure that the CLC completely fills the gap 3 between the facesurfaces 1, 2, including any small irregular volumes which are formedagainst or around the face surfaces 1, 2 or any components which arepositioned between these face surfaces 1, 2.

As can be seen in FIG. 4, a gap preferably exists between each support 5and the inner side of each face surface 1, 2, and this also allows theCLC to flow past each support 5 to fill the space between the facesurfaces 1, 2. The narrower, recessed regions of the sheets 42 alsoallow space for the CLC to flow past the supports 5. However, it is alsopreferred that the support structure includes a series of spaced apartsupport elements having opposite sides, with one face surface 1 beingattached to one of the sides, and the other face surface 2 beingattached to the other of the sides. It is preferred that the width ofeach of the support elements is substantially the same as, or slightlyless than, the distance between the inner sides of the two face surfaces1, 2.

In addition to this, the shape/volume or insulating properties of theCLC will not appreciably deteriorate over time, and the performance ofthe resulting wall 10 will therefore remain consistent over the life ofthe structure of which the wall 10 forms a part.

It is important to note that, in the example of the wall 10 given above,the CLC 9 acts as an insulating material, rather than as a structural orsupporting material. In conventional concrete structures, a volume isdefined between (for example), sheets of plywood, and concrete (having arelatively high density) is poured between the sheets to form a wall.After the concrete has set, the sheets of plywood are removed to leavethe finished wall as a structural or supporting element.

By contrast, in embodiments of the invention the structural rigidity ofthe wall 10 is provided primarily by the support structure, which ispositioned between the face surfaces 1, 2. The face surfaces 1, 2 remainin place as part of the completed wall 10, and provide additionalthermal and/or sound insulation, as well as providing an attractive andpresentable face on either side of the wall 10.

The sides of the face surfaces 1, 2 that face outwardly from the wall10, i.e. that are visible once the wall 10 has been constructed, can bemoulded or otherwise worked to have any suitable pattern orconfiguration.

These surfaces can be formed to be smooth and relatively featureless.Alternatively, the surfaces can be moulded to have an appearance akin tobrickwork or stonework, or any other desired pattern, texture orappearance.

This provides a high degree of flexibility to users regarding theappearance of the finished wall.

This may be of particular utility when one or more of the surfaces ofthe wall 10 will be on the exterior of a structure. Patterns resemblingbrickwork or stonework, for example, may be particularly desired inthese instances. In the example below the appearance of brickwork isused, but it should be understood that any other desired pattern,texture or appearance could also be used.

An example of a GRC sheet 35 which may be used for the first (i.e.external) face surface 1 is shown in FIG. 7. The sheet 35 is formed toresemble a section of conventional brickwork. The sheet 35 has generallystraight top and bottom edges 36, 37, and castellated left and rightedges 38, 39. The sheet 35 has divisions 40 formed thereon to resemblecement layers, so that the regions 41 between the divisions 40 have theappearance of a series (in the example shown, five rows of four) ofbricks. The sheet 35 may be sprayed, painted or otherwise coloured toresemble brickwork more closely.

A sheet of this kind has the advantage that the castellated left andright edges 38, 39 will fit together neatly, and help to ensure thatadjacent sheets are correctly aligned with each other. The serpentinejoin between adjacent sheets will also help to avoid having a straightvertical join, which would be more visible.

Sheets for use on the second (i.e. inner) face surface 2 may begenerally square or rectangular. The appearance of brickwork or othertextured surfaces on internal walls will be less commonly desired(although this may be appropriate for “loft” type interior decoration),and vertical joins between sheets are unlikely to be visible as internalwalls will be covered with render, wallpaper or another covering as partof the decoration/fit out process.

Walls formed in the manner described above will be less prone tovibration than conventional walls. Because the low viscosity CLC willsubstantially fill the entire space between the face surfaces 1, 2, thefinished structure will be solid and continuous, and resistant tovibration, or the transmission of vibration.

The combination of glass fibre reinforced board (particularly GRC) andCLC also provides advantageous protection against corrosion, and hasadvantageous fire resistant properties.

Referring to FIG. 8, a further aspect of the invention is shown.

FIG. 8 shows a pair of spaced apart walls 11, 12, each comprising (asdiscussed above) first and second face surfaces 1, 2 formed from glassfibre reinforced board. Support structures (such as series of supports 5of the type shown in FIG. 1) are positioned respectively within the twowalls 11, 12. In this example the support structure extends verticallyabove the level of the inner (second) face surface 2. Additionalcomponents such as water pipes, electrical cables and so on may beincluded within these walls 11, 12, as required, but are not shown inFIG. 7.

Between the top edges 14 of the inwardly-directed face surfaces 1, 2 ofthe two walls 11, 12 is a ceiling surface 15, which is once again formedfrom glass fibre reinforced board. The ceiling surface 15 is joined tothe top edges 14 of the inwardly-directed face surfaces 1, 2. As theskilled reader will understand, the ceiling surface 15 may be formedfrom a series of contiguous sheets of GRC, which are attached to theundersides of a series of horizontal support elements fixed in placeabove the ceiling surface 15, in a similar manner to the way in whichthe face surfaces 1, 2 are formed.

Above the level of the ceiling surface 15 a horizontal or substantiallyhorizontal support element (not shown), forming part of the supportstructure, is positioned and connected to the components of the supportstructure that extend within the walls 11, 12.

It will be understood that this formation of face surfaces 1, 2 and theceiling surface 15 provides a continuous internal space, extendingbetween the face surfaces 1, 2 of each wall 11,12, and above the ceilingsurface 15. This internal space is enclosed or substantially enclosed onall sides, except on its top (i.e. upward-facing side).

Once these components are in place CLC 17 is poured into this internalspace, so that the CLC 17 fills the spaces between the face surfaces 1,2 of the first and second walls 11, 12 and is filled up to a level abovethat of the ceiling surface 15, so that the CLC 17 completely covers theceiling surface 15 to a certain depth. In the example shown, this depthrises above the level of the horizontal support element, although thisis not essential.

Once the CLC 17 has set, it will be understood that a continuous,unitary and unbroken volume of CLC 17 is formed, extending within bothwalls 11, 12 and above the ceiling surface 15.

Using this technique, both the walls and the ceiling of a storey of abuilding structure can be formed in one step. This has severaladvantages over existing building methods.

Firstly, stories of a building can be constructed quickly. The facesurfaces 1, 2 and ceiling surface 15 can be formed either resting on aground level, or (if one or more storey has already been completed) ontop of an existing, completed storey. CLC can be poured into theresulting space in one step, filling the space to a depth which formsthe entire height of the walls and also at least part of the ceiling.Once the CLC has set, the storey is effectively completed. As discussedabove, there is no need to remove any of the face surfaces 1, 2 or theceiling surface 15.

With regard to thermal and sound insulation, the fact that the CLC formsa continuous, unitary and unbroken structure extending through the wallsand ceiling means that there are no gaps, breaks or joints which maytransmit heat or noise.

The formation of a storey in this way, including walls and a ceiling,may include a complex and/or irregular shape including both internal andexternal walls, and other features such as partitions, internal archesand so on. It is anticipated that, where a storey is formed in a singlestage in the manner described above, external walls will have a greaterthickness than internal walls, as external walls are likely to have arequirement for greater thermal and noise insulation. This will bediscussed in more detail below.

Particularly for a larger structure, the volume of CLC required to forma storey in a single stage may be very large. Where it is not possibleor practical to provide a sufficient quantity of liquid CLC to form theentire storey in one stage, the storey may be formed in two or moreoperations. However, it is preferred that, in situations such as this,the storey is divided into two or more sections, each of which includeswalls and a connected region of ceiling. In practice, a first sectionwill be prepared and filled with CLC so that the walls and ceiling areformed in one operation. Once this has been completed, CLC will (at alater time) be poured into a further section, once again filling thewalls and ceiling in one operation. Further sections may then becompleted as necessary.

It should be understood that, where a storey is completed in two or moreoperations, this is preferably not done by pouring CLC to fill the wholeor part of the storey up to a first height, allowing the CLC to set, andsubsequently pouring further CLC to fill the storey up to the level ofthe ceiling.

FIG. 9 shows in greater detail a junction between a wall of a first,lower storey, a ceiling of the first storey, and the wall of a second,immediately higher storey.

First and second face surfaces 1, 2 are provided as part of the firstwall 18, which is a wall of a first, lower storey. As discussed above,this lower storey may be a ground-floor storey, or may be a higher-levelstorey which is built on one or more existing stories.

The inner face surface 2 terminates at a top edge 14, and is joined atthis top edge 14 to a generally horizontal ceiling surface 15, asdescribed above.

The outer face surface 1 rises above the level of the top edge 14 of theinner face surface 2. In this embodiment, the outer face surface 1 risescontinually to form part of an upper wall, as described in more detailbelow.

A beam 19, which forms part of a support structure, is shown above theceiling surface 15, and it should be understood that this beam 19 willbe connected to other structural elements to form the support structure.

Low-density CLC 17 is poured into the space created by the first andsecond face surfaces 1, 2 and the ceiling surface 15, to fill entirelythe space between the first and second face surfaces 1, 2 and cover theceiling surface 15 to a set depth. In the embodiment shown this depth is200 mm, but any other suitable depth may be used.

The CLC 17 is allowed to set. As will be understood from the discussionabove, the first and second face surfaces 1, 2 and the ceiling surface15 remain in place, and will form part of the finished structure.

In the embodiment shown, a layer of wire mesh 16 is positioned above thelevel of the CLC 17. In the example shown in FIG. 4 the wire mesh 16 ispositioned on top of the beam 19. The wire mesh 16 extends in a plane(in the view shown in FIG. 4, perpendicular to the plane of the paper)and in preferred embodiments will rest on further beams (not shown)and/or other supporting members.

An inner face surface 20 for the wall 21 of the second, upper storey isplaced in position. Preferably, and as shown in FIG. 4, the inner facesurface 20 of the upper wall 21 is generally co-planar with the innerface surface 2 of the lower wall 18. The lower edge 22 of the inner facesurface 20 of the upper wall 21 preferably lies above the level of theCLC 17. This inner face surface 20 may be supported in position by anysuitable supports or restraints (not shown).

A top layer 23, which preferably comprises cement, is then poured on topof the CLC 17, to form a further layer which is above the CLC 17. Inpreferred embodiments the depth of this top layer 23 is less than thedepth that the CLC 17 extends above the ceiling surface 15, and in theembodiment shown this depth is 5 mm. The invention is not limited tothis, however.

On top of the top layer 23, a layer of a finishing surface 24, such astiles or carpet, is placed. The floor 25 of the upper storey is thencomplete and ready for use.

As will be seen from FIG. 8, when the top layer 23 is poured onto theCLC 17, this layer does not enter the space 26 between the inner andouter face surfaces 1, 20 of the upper storey wall 21. In order toensure that this does not occur, a surface or other blocking element(not shown) may be placed across the lower edges of the inner and outerface surfaces 1, 20.

As a next step, further CLC 17 is poured into the space between theinner and outer face surfaces 1, 20 of the upper storey, to form thewall 21 of the upper storey. As the skilled reader will appreciate, atthe upper end of this wall 21 (not shown), a further ceiling may beformed in one operation, as has been described above.

In the embodiment shown a bracing arrangement is provided to helpmaintain the correct alignment, and/or spacing between the variouscomponents during the construction process.

First and second anchoring angles are positioned within the lower andupper walls 18, 21, and may be held in place by any suitable meansbefore the CLC 17 is poured. The first anchoring angle 27 is provided atthe top of the first (lower) wall 18, and the second anchoring angle 28is provided at the bottom of the second (upper) wall 21.

A bolt 29 extends between the anchoring angles 27, 28, and is securedthereto by respective nuts 30.

A series of screws 31 pass through the anchoring angle and may be usedto secure the anchoring angles 27, 28 to one or more components (notshown) of the support structure.

In the discussion above, the walls and ceiling of a storey are formed inone operation. However, in alternative embodiments of the invention, thewalls and floor of a storey may be formed in one operation, and this isalso encompassed within the scope of the invention. The skilled readerwill appreciate how the steps set out above may be varied in order toform the floor and walls of a storey in one operation.

The discussion above states that all or most of the components of thesupport structure may be formed from light gauge steel. However, where astructure formed in accordance with the invention comprises severalstories, some of the components of the support structure may bereinforced by, or formed entirely from, heavier gauge steel, or one ormore other materials.

In implementation of the invention it is anticipated that a largeproportion of the construction work can be carried out on-site, withcomponents of the support structure and panels of glass fibre reinforcedboard being produced on-site, and CLC of an appropriate type also beingmixed to order on-site. This will allow greater efficiency and speed,and involve less environmental damage, than the fabrication of wholewalls or other building portions at a dedicated facility, which are thentransported to a site to be assembled into a finished buildingstructure.

Aspects of the present invention also relate to the planning of buildingstructures. In particular, the thickness of one or more walls of aproposed structure can be determined, prior to construction of the wall,based on a desired level of thermal and/or noise insulation. Theselevels may be set by legislation in one or more countries, or may bespecified by a client for whom a building is being constructed.

Where a wall is constructed of various layers, the thermal conductivity(also known as the K-value) of each material will be known. From thisthe material's R-value can be also be calculated—the R-value is ameasure of a material's capacity to resist heat flow from one side of alayer of the material to the other.

By considering each of the layers that make up a wall, and thethicknesses of these layers, the overall U-value of the wall can becalculated. The U-value of a wall (or other building component, such asa ceiling, roof or floor) is a metric of the amount of heat energy thatis transmitted through a square metre of the wall for every degree ofdifference in temperature between the inside and outside of the wall.U-values are typically expressed in W/m²K.

An example of a U-value calculation for an external wall comprising CLCbetween two boards of GRC is shown below:

Thickness K value (λ) R Value U Value Material (meter) W/mk Km2/W W/m2KOuter Skin 0.04 0.150 Coefficient GRC Board 0.015 1.2 0.01 CLC 150 KG/m30.272 0.042 6.48 GRC Board 0.012 1.2 0.01 Inner Skin 0.13 Coefficient6.67

Here the inner and outer skin coefficients will be determined byproperties of the inner and outer faces of the wall, and will beinfluenced by which paint etc. is used, as will be understood by theskilled reader.

A further example of a U-value calculation is given below for a floor,which comprises a ceiling layer formed of GRC board, with 0.2 m layer oflow-density CLC formed above the ceiling layer, and a 0.1 m layer ofhigher-density CLC formed on top of this. A thin layer of screed isformed on top of the high-density CLC.

Floor Thickness K value (λ) R Value U Value Material (meter) W/mk Km2/WW/m2K Inner Skin 0.17 0.188 Coefficient Screed 0.005 0.38 0.01 CLC 1100KG/m3 0.1 0.38 0.26 CLC 150 KG/m3 0.2 0.042 4.76 GRC Board 0.01 1.2 0.01Inner Skin 0.10 Coefficient 5.32

Based on these calculations, the U-value of a wall having a certainproposed construction can be compared to the U-value that is required,either by legislation or by a client's preference. This method can, ofcourse, be used to check that a proposed building structure will meetany set of given requirements.

However, the design of a wall (for example) may also be planned oraltered based on a desired U-value. For instance, the desired U-valuemay be stated, and thickness of the CLC layer (which is the parameter ofthe wall which is most easy to vary) may then be set so that the overallU-value of the wall is equal to the desired U-value, or exceeds thedesired U-value by a predetermined margin or factor (for instance, by10%).

In aspects of the invention, a storey of a structure is formed in asingle operation, as discussed above. The story may include severalsurfaces which are formed as part of this operation, for instance aseries of external walls, a series of internal walls, and a ceilingsurface. Each of these will have a minimum U-value.

As discussed above, the same CLC will be used to form all of thesevarious surfaces. In an aspect of the invention, the thickness of theCLC will be used to determine the thickness of each of the surfaces, sothat each surface meets (or exceeds, as discussed above, by a set marginor proportion) the required U-value. In this way, the thermal propertiesof the layers of each surface, including particularly the CLC, is usedto determine the thickness of the layer of CLC within each surface.

In general, an external wall will have a higher required U-value than aninternal wall. Where the same CLC is used to form an entire storey inone operation, the external walls will therefore likely be thicker thanthe internal walls, so that use of the same CLC results in the externaland internal walls all fulfilling their U-value requirements.

In certain embodiments the thickness of each surface formed during theformation of a storey may have at least the thickness required to giveit the desired U-value.

This technique is in contrast with conventional building approacheswhere an external wall may be formed from different materials comparedto, for example, an internal wall. Forming all of the major componentsof a storey of a structure in a single operation, using substantiallythe same materials, and varying the thicknesses of the CLC layers withinthe various components, allows a storey to be formed in a rapid andconvenient way, with all of the components fulfilling their requirementsfor thermal insulation.

In a further aspect of the invention, the thickness of at least onecomponent that will be formed during the formation of a storey of astructure, such as an external wall, may be pre-determined by otherfactors or considerations, or may only fall within a certain constrainedrange. In this case, the density of the CLC that is used to form thewall may be varied in order to achieve the desired U-value. As theskilled reader will be aware, the thermal conductivity of CLC will berelated to its density—the higher the density, the lower the thermalconductivity. If a first density of CLC (for instance, 150 kg/m³), usedwithin the set thickness for the external wall, does not give thedesired U-value, the density of the CLC may be increased (for instanceto 175 kg/m³, or 200 kg/m³) so that the wall provides the desiredU-value.

Once the density of CLC has been chosen, in preferred embodiments of theinvention the same density of CLC is used throughout the storey of thestructure when it is formed. This has the advantage of retaining thesimplicity, discussed above, of forming all of the major components of astorey of a structure in one operation.

Some aspects of the invention may be provided to be compatible with aBIM (building information modeling) platform, as will be understood bythose skilled in the art, although this is not essential.

In preferred embodiments of the invention, where a multi-storeystructure is created using techniques embodying the present invention, adifferent density of CLC may be used in different floors of thestructure. This may be because, in certain floors, there are factorswhich constrain the thickness of certain surfaces. Alternatively, theU-value requirements for different floors may vary.

The invention provides robust and flexible methods for rapid, efficientand cost-effective formation of building structures.

When used in this specification and claims, the terms “comprises” and“comprising” and variations thereof mean that the specified features,steps or integers are included. The terms are not to be interpreted toexclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the followingclaims, or the accompanying drawings, expressed in their specific formsor in terms of a means for performing the disclosed function, or amethod or process for attaining the disclosed result, as appropriate,may, separately, or in any combination of such features, be utilised forrealising the invention in diverse forms thereof.

1.-29. (canceled)
 30. A building structure comprising: a wall, the wallcomprising: inner and outer face surfaces formed from glass fibrereinforced board; a support structure comprising one or more rigidcomponents positioned between the inner and outer face surfaces; and aquantity of low-density cellular lightweight concrete (CLC) whichsubstantially fills the space between the inner and outer face surfaces,wherein: the building structure further comprises a ceiling or a floor,which forms part of the same storey of the structure as the wall,wherein the floor or ceiling comprises at least one face surface formedfrom glass fibre reinforced board, and the floor or ceiling contains aquantity of low-density CLC which forms a unitary, continuous andunbroken quantity of CLC along with the CLC which is within the wall.31. A building structure according to claim 30, wherein the inner andouter face surfaces of the wall are substantially parallel with eachother.
 32. A building structure according to claim 30, wherein thedensity of the CLC is less than 200 kg/m³.
 33. A building structureaccording to claim 30, wherein the face surfaces are formed from glassfibre reinforced concrete (GRC).
 34. A building structure according toclaim 30, wherein the low density CLC substantially fills the spacebetween the inner and outer face surfaces over the entire height of thewall.
 35. A building structure according to claim 30, wherein the innerand outer face surfaces are attached to, and supported by, the supportstructure.
 36. A building structure according to claim 35, wherein theface surfaces are spaced apart from the support structure, to provide agap between the support structure and each of the face surfaces.
 37. Abuilding structure according to claim 30, wherein the inner and outerface surfaces are each formed from a plurality of sheets of glass fibrereinforced board.
 38. A building structure according to claim 37,wherein the face surfaces are spaced apart from the support structure,to provide a gap between the support structure and each of the facesurfaces, wherein the support structure comprises a series ofspaced-apart supports, and each sheet is attached to at least one of thesupports.
 39. A building structure according to claim 38, wherein eachsupport has an inner side and an outer side, sheets of the inner facesurface are attached to the inner side and sheets of the outer facesurface are attached to the outer side.
 40. A building structureaccording to claim 37, wherein each sheet has widened regions atopposing edges thereof, with a narrower region between the widenedregions.
 41. A building structure according to claim 40, wherein eachsheet has widened regions at each of its edges.
 42. A building structureaccording to claim 30, wherein the support structure is entirely orsubstantially formed from light gauge steel (LGS).
 43. A buildingstructure according to claim 30, wherein the building structurecomprises two or more walls, each comprising inner and outer facesurfaces formed from glass fibre reinforced board, a support structurecomprising one or more rigid components positioned between the inner andouter face surfaces, and a quantity of low-density cellular lightweightconcrete (CLC) which substantially fills the space between the inner andouter face surfaces, and wherein the floor or ceiling contains aquantity of low-density CLC which forms a unitary, continuous andunbroken quantity of CLC along with the CLC which is within the walls.44. A building structure comprising two or more stories, each includinga wall and a floor or ceiling as recited in claim
 30. 45. A method offorming a building structure, the method comprising: providing inner andouter face surfaces for a wall formed from glass fibre reinforced board;providing a support structure, comprising one or more rigid componentspositioned between the inner and outer face surfaces; providing one ormore further face surfaces to define a ceiling space, above the wall, ora floor space, below the wall; and pouring a quantity of low-density CLCinto the space between the inner and outer face surfaces, and into theceiling space or the floor space, so that the wall is filled and theceiling space or floor space is filled, or partially filled, with thelow-density CLC in one operation.
 46. A method according to claim 45,wherein the method comprises: providing the support structure; attachingthe outer face surface to the support structure; and attaching the innerface surface to the support structure.
 47. A method according to claim46, further comprising the step, after the step of attaching the outerface surface to the support structure, but before the step of attachingthe inner face surface to the support structure, of installingcomponents of one or more service, such that, once the step of attachingthe inner face surface to the support structure has been completed, thecomponents of the one or more service are located between the inner andouter face surfaces.
 48. A method according to claim 47, wherein thecomponents of the one or more service include one or more of powercables, water pipes, data cables, and ventilation components.
 49. Amethod according to claim 45, further comprising the step of providingone or more further face surfaces for one or more further walls; andpouring the quantity of low-density CLC so that the walls aresubstantially filled, and the ceiling space or floor space is filled, orpartially filled, with the low-density CLC in one operation.